Since the usage of _preconnect is always guarded with ENABLE(SERVER_PRECONNECT), its declaration should be guarded with it as well.
<rdar://problem/64139060>
Created attachment 401396 [details] Patch
Committed r262756: <https://trac.webkit.org/changeset/262756> All reviewed patches have been landed. Closing bug and clearing flags on attachment 401396 [details].